Wilson D M, Ottina K, Newman M J, Tsuchiya T, Ito S, Wilson T H
Membr Biochem. 1985;5(4):269-90. doi: 10.3109/09687688509150282.
Different conditions were studied for optimal solubilization and reconstitution of the melibiose carrier of Escherichia coli. Several alpha- and beta-galactosides, known to be substrates for the melibiose carrier, were found to inhibit [3H]-melibiose uptake by proteoliposomes. In the presence of 10 mM Na+ the Km for melibiose counterflow was 0.42 mM. Melibiose and raffinose were good substrates for counterflow, while thiomethyl-beta-galactoside and p-nitrophenyl-alpha-galactoside were accumulated very poorly. Although the latter two sugars are known to be substrates for the carrier, they showed a very rapid rate of passive diffusion across the liposome membrane. The proton ionophore carbonylcyanidechlorophenylhydrazone had no effect on uptake, suggesting that a proton motive force is not essential for the counterflow phenomenon.
研究了不同条件以实现大肠杆菌蜜二糖载体的最佳增溶和重组。发现几种已知为蜜二糖载体底物的α-和β-半乳糖苷可抑制[³H]-蜜二糖被蛋白脂质体摄取。在10 mM Na⁺存在下，蜜二糖逆向流动的Km为0.42 mM。蜜二糖和棉子糖是逆向流动的良好底物，而硫代甲基-β-半乳糖苷和对硝基苯基-α-半乳糖苷的积累很差。尽管后两种糖已知是载体的底物，但它们在脂质体膜上的被动扩散速率非常快。质子离子载体羰基氰化物氯苯腙对摄取没有影响，这表明质子动力对于逆向流动现象不是必需的。
